Eh, it's a good shower thought.
But I have to disagree overall. Both of them showed interest in various subjects; Harry more than Ron.
But, I think you're right that the magic system is boring. It's memorizing fiddly combinations of words and movements.
Rowling didn't really set out to write a magic series. She was writing a boarding school series with a magical background, so she never did any proper world building. What little there is came well after the movies exploded, and is largely cobbled together.
While not as well written, it has much closer ties to things like the Chronicle of Narnia than something like Sanderson's stuff. The magic is fluff, technobabble, not what the series is actually about.
If there had been sections set in muggle schools, Harry and Ron would have been roughly the same. Harry likely would have been interested in some subjects, but distracted by the real story, while Ron would have been kind of drifting along, getting by grade wise without being interested. Ron might have been semi into soccer, but have been whining about it not being as good as quiddich.
I would also argue that if Sanderson, or a similarly world building capable author, had taken on the story, there still would have been a gradation in the trio's academic focus. You take three kid characters and have them being exactly the same about something like that, it won't work; you'd end up having to completely hand wave it with references to them being great students because it's more boring to have them all be the same level of interest in any given thing.
Even among real world scholarly sorts, the levels of interest in a given subject aren't going to be exactly the same, and a lot of those kids tend to start their friendships because of the "nerd" factor. The HP trio became friends partially by accident, but stayed friends as they grew together and shared experiences, so the dynamics just aren't the same.
Even the last three books, where it seems like there's discovery of an underlying system to the magic, the deathly hallows are a mcguffin, not a genuine world building tool.
So, I get where you're coming from, and agree that she did a pretty crappy job of making a coherent magic system. But it didn't really need one, it just needed silly phrases for kids to geek out over, and that she did very well